Oled display with contrast enhancing interference members

ABSTRACT

The present invention introduces a novel design for active matrix displays, utilizing both organic light-emitting diode (OLED) and thin-film electroluminescent technologies. In a first aspect there is provided a top-emitting OLED, including an optical interference contrast-enhancing stack that is placed on the top of the driving thin-film transistor, and which extendes to the entire pixel area to cover the reflecting parts of the pixel. In a second aspect, there is provided a bottom-emitting OIED wherein an optical interference contrast-enhancing stack is placed right under the driving thin-film transistor and, separately between the organic stack and the top electrode, typically a cathode. The optical interference contrast-enhancing stack suppresses light reflection from the thin-film transistor and the upper electrode. In the top emitting design, the optical interference contrast-enhancing stack is placed on the top of the thin-film transistor source and drain electrodes as well as on the top of the opaque bottom electrode. A method of achieving substantial uniformity across a display having multiple areas of optical interference members is also provided.

PRIORITY CLAIM

The present application claims priority from U.S. Patent Application No.60/387,414 filed Jun. 11, 2002, the contents of which are incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates generally to display technologies and moreparticularly to relates to reduction of ambient light reflections off ofdisplays.

BACKGROUND OF THE INVENTION

Many display technologies are well known and such technologies arecontinuing to advance rapidly. For example, modem active matrix displaytechnology can be incorporated into display devices that are relativelylightweight, thin, and which provide high resolution and richly colouredpictures for televisions, computer monitors, and more generally, for awide variety of display devices that can be incorporated into applianceslike personal digital assistants and cellular telephones. While currentactive matrix displays can be expensive, it is expected that furtherresearch will result in advances that will can reduce the costs of suchdisplays and lead to overall greater usage of active matrix displaydevices.

Active matrix displays are proving to be superior in many ways to olderdisplay technologies such as cathode-ray tubes (“CRT”). However, theproblem of “glare” off of active matrix displays is also a concern, justas with older CRTs. “Glare” can be defined as ambient light that isreflected off of the device and back towards the viewer, therebyreducing the contrast and overall performance of the display device.

Thus, it is also known to incorporate technology to reduce reflectanceinto displays and thereby improve their performance. In the case ofactive matrix displays (or indeed, any other type of pixellated display)it is known to use a black matrix of filtering material. The blackmatrix is mounted in a complementary fashion to the matrix of pixels inthe display, such that the black matrix is a generally continuous filterthat surrounds each pixel. Black matrices are described in a number ofpatents and patent applications, such as “Anti-reflector black matrixfor use in display devices and method for preparation of same”, EP 716334 to Steigerwald (“Steigerwald #1”); “Transmissive Display DeviceHaving Two Reflection Metallic Layers of Differing Reflectances”, U.S.Pat. No. 6,067,131 to Sato (“Sato”); “Anti-reflector black matrixdisplay devices comprising three layers of zinc oxide, molybdenum andzinc oxide”, U.S. Pat. No. 5,570,212 to Steigerwald (“Steigerwald #2”);“Anti-reflector Black Matrix Having Successively A Chromium Oxide Layer,a Molybdenum Layer And a Second Chromium Oxide Layer”, U.S. Pat. No.5,566,011 to Steigerwald (“Steigerwald #3”); and, “Low ReflectanceShadow Mask”, U.S. Pat. No. 5,808,714 to Rowlands et al. (“Rowlands”).One particular disadvantage to Steigerwald #1, Steigerwald #2Steigerwald #3 and Rowlands is that they are confined to black matrixstructures having specific sets of materials. A more general discussionof applying a black matrix as applied to a display having colour filtersis found in U.S. Pat. No. 5,587,818 to Lee (“Lee”).

However, such prior art black matrix structures are not always useful orpractical to incorporate into display devices. For example, prior artblack matrix structures are frequently formed as a separate unit fromthe display, thereby eventually requiring the assembly of the blackmatrix structure to the display structure, such as by mounting the blackmatrix structure to the front of the display.

It is also known to use optical interference to reduce reflectance invarious thin film display technologies, such as electroluminescentdevices (“ELD”s). For example, reducing reflectance of ambient light canbe achieved by using additional thin film layers sandwiched between oneor more layers of the ELD, which are configured to achieve destructiveoptical interference of the ambient light incident on the display,thereby substantially reducing reflected ambient light. Opticalinterference technology is discussed in detail in U.S. Pat. No.5,049,780 to Dobrowolski et al., (“Dobrowolski”) and U.S. Pat. No.6,411,019 to Hofstra et al. (“Hofstra”). In addition, certain inventorsof the present invention have also contemplated the use of the opticalinterference technology taught in Hofstra and Dobrowolski in conjunctionwith the bus lines that form the matrix surrounding each pixel in anactive matrix display. See Canadian Patent Application 2,364,201 filedDec. 12, 2001.

More recently, U.S. Pat. No. 6,429,451 to Hung (“Hung”) has proposedanother type of ambient light reducing layer also for incorporation intoa pixel of the ELD.

However, notwithstanding the improvements provided by the prior art, itis now been discovered that the prior art does not provide ambient lightreduction across all areas of the display, as is now offered bypolarizers that are also used with prior art displays. Becausepolarizers can offer substantially uniform ambient light reductionacross the entire viewable surface of the display, polarizers can bepreferred over other prior art solutions that embed or otherwiseincorporate the ambient light reduction means within the actual displaystructure. In order to obviate the need for polarizers and achieve theattendant advantages eliminating the post production costs associatedwith polarizers, it is desired to provide a means to substantiallyuniformly reduce ambient light reflection across the entire viewablesurface of the display by means of embedding the contrast enhancementapparatus within the display.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a displaythat obviates or mitigates at least one of the disadvantages of theprior art.

An aspect of the invention provides a display device comprising aplurality of emitting pixels and at least one switching electroniccorresponding to each pixel for selectively activating or deactivatingthe pixel. The device also comprises at least one additional componentfor interconnecting the pixels and the switching electronics, and atleast two ambient light reducing members each integrally embedded intoat least one of: a) the pixels, b) the switching electronics and c) theat least one additional component. The ambient light reducing membersare disposed in a plane that is visible to a viewer and are selectedfrom materials and thicknesses such that the reduced ambient lightreflections in the plane are substantially uniform.

The emitting pixels can be bottom emitting or top emitting. The at leastone additional component can be a set of bus lines for deliveringelectrical current to the pixels and the switching electronics.

The emitting pixels can be comprised of an OLED stack and wherein atleast one of the ambient light reducing members is integrated with theOLED stack.

The at least one of the ambient light reducing members can be integratedwith the switching electronics. The at least one ambient light reducingmembers can thus form part of the electronic circuitry of the switchingelectronics. The switching electronics can include at least onetransistor and the ambient light reducing member can be a storagecapacitor for the at least one transistor.

The ambient light reducing member can be an optical interference member.Where an optical interference member is used it can include asemi-absorbing layer for reflecting a portion of incident ambient light,a substantially transparent layer for phase shifting another portion ofambient light and a reflective layer for reflecting the phase shiftedambient light such that the two reflected portions of light areout-of-phase and thereby destructively interfere.

Another aspect of the invention provides a display device comprising aplurality of emitting pixels. The device also comprises at least oneswitching electronic corresponding to each pixel for selectivelyactivating or deactivating the pixel. The device also comprises at leastone additional component for interconnecting the pixels and theswitching electronics. An ambient light reducing member is integrallyembedded into the switching electronic to form part of an electroniccircuitry of the switching electronics. The ambient light reducingmember is disposed in a plane that is visible to a viewer and selectedfrom materials and thicknesses to reduce ambient light reflections. Theelectronic switching components include at least one transistor and theambient light reducing member is a storage capacitor for the at leastone transistor.

Another aspect of the invention provides a computer implemented methodof matching the reflectance between different ambient light reducingmembers in a display comprising the steps of:

-   -   receiving a first set of data representing an initial        specification for a first set of components in an active display        device;    -   determining, based on the first set of data and a predefined        database of ambient light reducing member configurations, a        first ambient light reducing member for incorporation into the        first set of components;    -   receiving at least one additional set of data representing an        initial specification for at least one additional set of        components in the active display device;    -   determining, based on the at least one additional set of data        and the predefined database, at least one additional ambient        light reducing member for incorporation into the at least one        set of components;    -   generating a model of the active display device based on an        assembly of the first set of data, the first ambient light        reducing member, the at least one additional set of data, and        the at least one additional ambient light reducing member;    -   measuring ambient light reflectance across the model;    -   determining whether the measured reflectance is substantially        uniform and, if the reflectance is non-uniform, reconfiguring at        least one of the specifications and the ambient light members        until a desired level of uniformity is achieved; and,    -   outputting a final specification for the display.

The first set of components in the method can be light emitting pixelsand the at least one additional set of components can be switchingelectronics corresponding to the light emitting pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only,with reference to certain embodiments shown in the attached Figures inwhich:

FIG. 1 is a schematic representation of at least a portion of a matrixdisplay;

FIG. 2 is a schematic representation of a cross-section of a singlebottom-emitting pixel such as may be found in the display of FIG. 1 andthat is in accordance with an embodiment of the invention;

FIG. 3 is a flow chart depicting a method of providing contrastenhancement to the pixel of FIG. 2 and the display associated therewith;

FIG. 4 is a schematic representation of a cross-section of a singlebottom-emitting pixel in accordance with another embodiment of theinvention;

FIG. 5 is a schematic representation of a cross-section of a singlebottom-emitting pixel in accordance with another embodiment of theinvention;

FIG. 6 is a schematic representation of a cross-section of a singlebottom-emitting pixel in accordance with another embodiment of theinvention;

FIG. 7 is a schematic diagram representative of the electrical circuitof the pixel in FIG. 6;

FIG. 8 is a schematic representation of a cross-section of twotop-emitting pixels in accordance with another embodiment of theinvention; and,

FIG. 9 is a schematic representation of a cross-section of atop-emitting pixel in accordance with another embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1 at least a portion of an exemplary matrixdisplay is indicated generally at 20. Display 20 comprises a pluralityof pixels 24 (only one of which is labelled). Each pixel 24 issurrounded by a grid of bus lines 28 and is adjacent to a set ofelectronic components 32 respective to that pixel. FIG. 2 shows aparticular implementation of display 20 in FIG. 1, by showing aparticular pixel through lines Z-Z in FIG. 1. In particular, FIG. 2shows a bottom emitting display configuration with a pixel 24 a and itsadjacent electronic components 32 a. A viewer V in FIG. 2 shows the sidefrom which pixel 24 a is viewed, and thus from which ambient light isincident on pixel 24 a. Pixel 24 a is preferably based on organic lightemitting display (“OLED”) technology that includes one or more opticalinterference layers 26 a for ambient light reduction, such as thattaught in Hofstra. Electronic components 32 a include a switchingelectronics layer 36 a that is comprised of a transistor or otherswitching means for selectively actuating pixel 24 a via an interconnect28 a. Electronic components 32 a also includes an insulator 38 adisposed below switching electronics layer 36 a, and an opticalinterference member 40 a disposed below insulator 38 a. Opticalinterference member 40 a and pixel 24 a are themselves disposed above aglass substrate 44 a. Insulator 38 a is any material and thickness thatwill electrically isolate optical interference member 40 a fromswitching electronics layer 36 a. An additional optical interferencemember 48 a is disposed behind both pixel 24 a and switching electronicslayer 36 a. (Optical interference member 48 a can be associated with anyother aspects of the display, such as, for example the bus lines thatinterconnect the switching electronics layer 36 a.)

It should be noted that terms such as “above” and “below” are usedherein for convenience and are to be read in conjunction with thedrawings, and as such are not to be construed in a limiting manner.

As previously mentioned, optical interference members 26 a, 40 a and 48a can be based on known formulations of optical interference members, astaught in, for example Hofstra and/or according to other desired meansof formulating an optical interference member. However, due to thevirtually infinite number of formulations of optical interferencemembers the potential can arise for variations between those differentformulations such that while all formulations may appear “dark” and haveacceptable performance on their own, when different formulations areplaced side by side, contrasts between those formulations may bedetectable in an undesired way, such that the overall “darkness” of thedisplay is non-uniform.

Accordingly, referring now to FIG. 3, in an another embodiment of theinvention a method of matching the reflectance between different opticalinterference members in a matrix display is indicated generally at 100.Method 100 is specifically configured to be used to develop a display inaccordance with the pixel 24 a and switching electronics 36 a of FIG. 2,but it is contemplated that method 100 can be modified for use withother types of matrix display configurations. Before beginning method100, it is thus assumed that the matrix display being designed is inaccordance with the configuration of FIG. 2, and that designspecifications relating to the display technology for pixel 24 a, thepitch of each pixel 24 a, the fill factor, and the like have beenpreviously established. Thus, beginning at step 110, the specificationsfor each emitting pixel are each determined. Factors to be determinedinclude the emitting technology, the power requirements for switchingthe pixel, the colour of the pixel, the materials and thicknesses forthe pixel. Next, at step 120, an initial optical interference membercorresponding to the specifications determined at step 110 is generatedusing known techniques, such as the techniques taught in Hofstra. Inparticular, various materials and thicknesses are selected for opticalinterference member 26 a in order to provide at least some reduction ofincident ambient light on pixel 24 a. Further, optical interferencemember 26 a is designed to cooperate with the desired electricalcharacteristics to operate pixel 24 a. In general, it is expected thatthe initial optical interference member will be coarsely calculated tomatch the other desired specifications of the emitting pixel, whileproviding a reduction of incident ambient light on pixel 24 a. At step130, the specifications for switching electronics 36 a are determined.It is generally expected that the specifications for switchingelectronics 36 a will thus be chosen to correspond with the electricalproperties needed to activate and deactivate pixel 24 a, while alsomatching with the other previously chosen specifications for thedisplay. Next, at step 140, an initial optical interference member 40 acorresponding to the specifications determined at step 130 is generatedusing known techniques. In particular, various materials and thicknessesare selected for optical interference member 40 a in order to coatswitching electronics 36 a such that reflections off of switchingelectronics 36 a are reduced. In this embodiment, optical interferencemember 40 a is electrically conducting and it is therefore desired toalso include insulator 38 a to isolate electronics 36 a from member 40a. In general, optical interference member 40 a is chosen to cooperatewith the desired electrical characteristics of switching electronics 36a, while providing a reduction of incident ambient light on switchingelectronics 36 a. Similarly, at step 150, an initial opticalinterference member 48 a is generated using appropriately selectedmaterials and thicknesses in order to provide an additional insulatingoptical interference member that coats all or part of the area behindelectronics 36 a and pixel 24 a and which provides ambient lightreduction for incident ambient light that is not otherwise reduced byoptical interference members 26 a and 40 a.

Next, at step 160, a complete model for a display is assembled using theresults of steps 110-150. Such a model can be assembled by physicallybuilding a sample display and/or through computer modeling. At step 170,the uniformity of ambient light reflection reduction from opticalinterference members 26 a, 40 a and 48 a is measured. Where a physicalmodel has been built, then such measurements are effected usingmeasurement equipment using various ambient light conditions, and in thecase of a computer model then simulated measurements are taken based onsimulated ambient light conditions. Sample ambient light conditions caninclude direct sunlight, room lighting, and so forth, depending on theexpected operating environment for the display.

At step 180, a determination is made as to whether the measureduniformity is acceptable. If yes, the method advances to step 190 andfull production of the display can be commenced. However, typically theuniformity will not be acceptable on the initial design and the methodadvances to step 200, where the greatest level of disparity inuniformity is determined. The method advances to steps 210, 220 or 230depending on whether the greatest disparity is caused by the opticalinterference member 26 a, 40 a or 48 a, respectively. At those steps210, 220 or 230, modifications to the corresponding optical interferencemember 26 a, 40 a or 48 a are effected (and/or effected to theassociated component), at which point the method returns to step 160where a new matrix display model is generated. The method then movesagain through steps 170 and 180 and through the remaining steps asneeded until an acceptable uniformity level is achieved.

Method 100 is preferably implemented in computer software that includesknown material sets and thicknesses ranges for developing opticalinterference members, and associated design specification for associatedpixels and switching electronics. In this manner, a substantiallyuniformly dark matrix display can be modeled and developed in a timeefficient manner.

It is presently preferred that the difference between the reflectivitiesof each optical interference member (or other ambient light reducingmember) be less than about ten percent. More preferably, the differencebetween the reflectivities is less than about three percent. Morepreferably, the difference between the reflectivities is less than aboutone percent. It is presently preferred that the difference between thereflectivities is less than about 0.5 percent.

An optical interference member (such as optical interference members 26a, 40 a or 48 a) can be based on a three layer structure of: i) asemi-absorbing layer that is partially reflective, partially absorbingand partially transmissive of ambient light, ii) a substantiallytransparent layer that phase shifts the incoming ambient light, and iii)followed by a reflective rear layer (which may be electrically part ofthe pixel or other component with which the optical interference memberis associated, or not, as desired). Where the optical interferencemember is based on this structure, then the software will be optimizedto choose materials and thicknesses based on the appropriatefunctionalities of those layers. Thus, the software package will lookfor materials and thicknesses of the semi-absorbing layer such that aportion of ambient light incident on the member is partially reflectedoff of the member, while a remaining portion passes into the partiallytransmissive layer therebehind. The software will then choosethicknesses and materials for the partially transmissive layer such thata phase shift of about one-hundred-and eighty-degrees occurs in theambient light passing through partially transmissive layer. The finalreflective rear layer is chosen to provide sufficient reflection, and/orhave appropriate electrical properties. The overall optical interferencemember may be work function matched for an OLED pixel, and/or may beotherwise electrically matched with its surrounding materials. Thesoftware will thus include a database of possible materials for asemi-absorbing layer that includes Cr, Al, Mg:Ag, inconel or Ni, Cu, Au,Mo, Ni, Pt, Rh, Ag, W, Co, Fe, Ge, Hf, Nb, Pd, Re, V, Si, Se, Ta, Y, Zr.The software will thus include a database of possible materials for apartially reflecting material that includes Aluminum Silicon Monoxide,Chromium Silicon Monoxide, Al₂O₃, SiO₂, ZrO₂, HfO₂, Sc₂O₃, TiO₂, La₂O₃,MgO, Ta₂ O₅, ThO₂, Y₂O₃, CeO₂, AlF₃, CeF₃, Na₃ AlF₆, LaF₃, MgF₂, ThF₄,ZnS, Sb₂O₃, Bi₂O₃, PbF₂, NdF₃, Nd₂O₃, Pr₆O₁₁, SiO, NaF, ZnO, LiF, GdO₃.

The software can also include databases of other types of opticalinterference members based on other types of structures (i.e. the typeof structure in PCT/CA02/00844, or PCT/CA03/00498, incorporated hereinby reference), so that a plurality of different types of opticalinterference members can be selected in order to achieve the desireduniformity.

The embodiments in FIG. 3 can be modified and/or varied and/or otherwiseapplied to various display configurations. For example, FIG. 4 shows abottom emitting display configuration with a pixel 24 b and its adjacentelectronic components 32 b. A viewer V in FIG. 4 shows the side fromwhich pixel 24 b is viewed, and thus from which ambient light isincident on pixel 24 b. The display configuration in FIG. 4 is thussubstantially the same as the display configuration in FIG. 2, exceptthat insulator 38 a is omitted. In this case the materials selected foroptical interference member 40 b are preferably non-conducting so as tonot interfere with switching electronics 36 a.

As another example, FIG. 5 shows another bottom emitting displayconfiguration with a pixel 24 c and its adjacent electronic components32 c. A viewer V in FIG. 5 shows the side from which pixel 24 c isviewed, and thus from which ambient light is incident on pixel 24 c. Thedisplay configuration in FIG. 5 is thus substantially the same as thedisplay configuration in FIG. 4, except that two optical interferencemembers 40 c 1 and 40 c 2 are provided proximal to switching electronics36 c. Optical interference members 40 c 1 and 40 c 2 can be the samestructure or different, and thus the method in FIG. 3 would be modifiedto accommodate determining whether substantial uniformity is achievedfor all optical interference members 26 c, 40 c 1, 40 c 2 and 48 c.Optical interference member 40 c 1 performs substantially the samefunction as optical interference member 40 b, reducing ambient lightthat is incident on glass substrate 44 c. Optical interference member 40c 2, however, is reversed, so that it reduces reflections of light thatemanate off of the back of the display (i.e. the side opposite fromglass substrate 44 c). Typically, optical interference member 40 c 2 isdesigned to reduce pixel blooming, to reduce backward reflections ofemitted light from pixels adjacent to pixel 24 c. It should now beapparent that the configurations in the examples of FIGS. 2, 4, and 5can be combined as well to produce additional examples.

In general, it should be understood that the structures in FIGS. 2, 4and 5 are simplified for purposes of explanation. A somewhat morecomplex example, shown in FIG. 6, is another bottom emitting displayconfiguration with an optical interference member 40 d that is integralwith its surrounding switching electronics, such that opticalinterference member 40 d forms a dual function as a storage capacitor asa gate 201 d as part of the switching electronics for activating an OLEDbased pixel 24 d. A circuit diagram representing the components in FIG.6 is shown in FIG. 7 and is indicated at 300.

Of particular note, optical interference member 40 d acts as a storagecapacitor to hold the charge that is used to activate the transistorthat ultimately provides current to pixel 24 d in order to cause pixel24 d to emit light. Concurrently, optical interference member 40 d actsto mask the switching electronics used to activate pixel 24 d.

Switching electronics also includes a drive TFT 212 d, that itselfincludes a semi-conductor 204 d, which can be made from CdSe, or a-Si orpoly-Si. Drive TFT 212 d also includes a source 202 d, a drain 206 d, achannel 208 d, and a substrate 200 d.

FIG. 7 also shows a data transistor 216 d, (not shown in FIG. 6), thatconnects as shown in FIG. 7 to optical interference member 40 d. Data isintroduced to data transistor 216 d along arrow A, and a select signalis provided to data transistor 216 d along arrow B.

It is to be noted that optical interference members 40 d and 48 d are ofthe above-described three-layer format, but other optical interferencemember configurations are contemplated. The composition of the opticalinterference member may depend on the particular application. Theinitial, semi-absorbing layer 48 d 1 can be Cr, Al, Ag, Mg, Cs, Pt, Au,Li, and their alloys. They can be deposited using thermal evaporation,e-beam, or sputtering techniques. The subsequent substantiallytransparent phase shifting layer 48 d 2 (which is also conducting inthis embodiment) can be made of AlSiO, CrSiO, chrome oxide, zinc oxide,indium tin oxide, indium oxide, and other transparent conducting oxides.

(In other embodiments, an insulating phase shifting layer can be made ofSiO, SiO2, Si3N4, SiON, ZnO, and other dielectric materials.)

The semiconductor component of thin-film transistors may utilizeamorphous silicon, poly-silicon, continuous-grain silicon, cadmiumselenide, and/or other suitable semiconducting materials. An exemplarytechnological method to fabricate the display in FIG. 6 is as follows:The bottom transparent electrode is fabricated first on a glass (orflexible plastic) substrate 44 d using standard patterning methods.Next, the optical-interference member 40 d stack is fabricated proximalto the thin film transistor 212 d part of the pixel 24 d using thermalevaporation, electron-beam evaporation, or sputter deposition techniquesand masking and patterning techniques known in the art. Next, theactive-matrix drive circuitry is deposited then, usingstandard-fabrication methods. Next, a small-molecule or polymer organiclight-emitting stack (ie pixel 24 d) is then deposited followingwell-known deposition techniques. Then, the optical interference member48 d is then deposited again to increase contrast of the emitting partof the pixel 24 d. The device is then encapsulated using techniquesknown in the art.

As another example, FIG. 8 shows a top emitting display configurationwith two pixels 24 e and corresponding electronic components 32 edisposed therebelow, all of which are disposed above a glass substrate44 e. The top emitting OLED pixel 28 e includes an optical interferencemember 26 e. Electronic components 32 e include switching electronics 36e and a contiguous insulating optical interference member 48 e. Aninterconnect 28 e joins switching electronics 36 e with the anode ofpixel 28 e. Optical interference member 48 e serves to reduce ambientlight incident on the display in the areas that are not reduced via theoptical interference member 26 e of each pixel 24 e. The method of FIG.3 can thus be modified to choose appropriate optical interferencemembers 26 e and 48 e and thereby attain a substantially uniformreduction of ambient light across the entire display.

It should now be apparent that other configurations of top emittingdisplay configurations, other than those in FIG. 8, can also be formed.For example, the double sided optical interference members 40 c 1, 40 c2 of FIG. 5 can be incorporated into the display configuration of FIG.8, so that the rearward reflections of each pixel can be reduced andthereby reduce the effects of pixel blooming.

FIG. 9 shows a further example of a top-emitting pixel configuration,wherein a three layered optical interference member 26 f lies betweenswitching electronics 36 f and OLED pixel 24 f, and accordingly, opticalinterference member 26 f masks the complete set of underlying switchingelectronics 32 f. Optical interference member 26 f forms part of, or isadjacent to, the anode of the OLED pixel 24 f, and therefore conductscurrent from switching electronics 32 f to OLED pixel 24 f. In thisembodiment, the bus lines interconnecting the switching electronics 32 fare not shown, and are also coated with an optical interference member.Accordingly, the method of FIG. 3 can be modified so that the opticalinterference member coating the bus lines can be matched for reflectanceuniformity with optical interference member 26 f.

While only specific combinations of the various features and componentsof the present invention have been discussed herein, it will be apparentto those of skill in the art that desired subsets of the disclosedfeatures and components and/or alternative combinations of thesefeatures and components can be utilized, as desired. For example, otherdisplay technologies can be used instead of OLED light-emittingpixels—such as inorganic or TFEL light emitting pixels. As anotherexample, each pixel could be a shutter means that passes light emittedfrom a back light when the pixel is activated.

Furthermore, for each OLED pixel 24, the optical interference member 26embedded therein can be made of materials that directly work functionmatches with the emitting organic material of the optical interferencemember 26, or, a work function matching layer of LiO, LiF or the likecan be inserted between the optical interference member 26 and theemitting layer of the pixel 24 in order to provide work functionmatching.

It is to be further understood that the examples of FIGS. 2, 4, 5, 6, 8and 9, and/or their combinations can be fabricated in a plurality ofmanners. In particular, once the overall display is designed, it iscontemplated that in the configuration of FIG. 4 (for example), opticalinterference layer 40 b can be deposited onto substrate 44 b, for latermating with a configuration that includes the remaining components shownin FIG. 4. In this manner, a large batch of substrates 44 b that includeoptical interference layer 40 b can be manufactured at one facility tobe later mated with the remaining components at another manufacturingfacility. Such variations are within the scope of the invention.

Furthermore, while the embodiments herein discuss ambient light reducinglayers based on optical interference, it is contemplated that othertypes of ambient light reducing layers that can be integrallyincorporated into the various layers of a display can also be used inthe method of FIG. 3, in lieu of, or in addition to optical interferencelayers. As is known to those of skill in the art, such other layers canbe simply based on carbon “dark layers” that absorb incident ambientlight. Other types of “dark layers” will now occur to those of skill inthe art. Thus, the method of FIG. 3 can be thus be implemented on acomputing device that includes a database of all known such dark layers,(with new layer designs and design techniques added to the database asthey are developed) and the appropriate dark layer can be chosen for aparticular electronic component in a given display in order to achievesubstantial uniformity across the viewing plane of the display.

1. A display device comprising: a plurality of emitting pixels; at leastone switching electronic corresponding to each said pixel forselectively activating or deactivating each said pixel; at least oneadditional component for interconnecting said pixels and said switchingelectronics; at least two ambient light reducing members each integrallyembedded into at least one of: a) said pixels, b) said switchingelectronics and c) said at least one additional component; said ambientlight reducing members being disposed in a plane that is visible to aviewer and selected from materials and thicknesses such that reducedambient light reflections in said plane are substantially uniform. 2.The display device according to claim 1 wherein said emitting pixels arebottom emitting.
 3. The display device according to claim 1 wherein saidemitting pixels are top emitting.
 4. The display device according toclaim 1 wherein said at least one additional component is a set of buslines for delivering electrical current to said pixels and saidswitching electronic.
 5. The display device according to claim 1 whereinsaid emitting pixels are comprised of an OLED stack and wherein at leastone of said ambient light reducing members is integrated with said OLEDstack.
 6. The display device according to claim 1 wherein at least oneof said ambient light reducing members is integrated with said switchingelectronic.
 7. The display device according to claim 6 wherein at leastone of said ambient light reducing members forms part of a circuitry ofsaid switching electronic.
 8. The display device according to claim 7wherein said switching electronic includes at least one transistor andsaid ambient light reducing member is a storage capacitor for said atleast one transistor.
 9. The display according to claim 1 wherein saidambient light reducing member is an optical interference member.
 10. Thedisplay according to claim 9 wherein said optical interference memberincludes a semi-absorbing layer for reflecting a portion of incidentambient light, a substantially transparent layer for phase shiftinganother portion of ambient light and a reflective layer for reflectingsaid phase shifted ambient light such that said two reflected portionsof light are out-of-phase and thereby destructively interfere.
 11. Adisplay device comprising: a plurality of emitting pixels; at least oneswitching electronic corresponding to each pixel for selectivelyactivating or deactivating said pixel; at least one additional componentfor interconnecting said pixels and said switching electronics; and, anambient light reducing member integrally embedded into said switchingelectronic to form part of an electronic circuitry of said switchingelectronic, said ambient light reducing member being disposed in a planethat is visible to a viewer and selected from materials and thicknessesto reduce ambient light reflections.
 12. The display device according toclaim 11 wherein said electronic switching component includes at leastone transistor and said ambient light reducing member is a storagecapacitor for said at least one transistor.
 13. A computer implementedmethod of matching the reflectance between different ambient lightreducing members in a display comprising the steps of: receiving a firstset of data representing an initial specification for a first set ofcomponents in an active display device; determining, based on said firstset of data and a predefined database of ambient light reduction memberconfigurations, a first ambient light reducing member for incorporationinto said first set of components; receiving at least one additional setof data representing an initial specification for at least oneadditional set of components in said active display device; determining,based on said at least one additional set of data and said predefineddatabase, at least one additional ambient light reducing member forincorporation into said at least one set of components; generating amodel of said active display device based on an assembly of said firstset of data, said first ambient light reducing member, said at least oneadditional set of data, and said at least one additional ambient lightreducing member; measuring ambient light reflectance across said model;determining whether said reflectance is substantially uniform based onsaid measuring step and, if said reflectance is non-uniform,reconfiguring at least one of said specifications and said ambient lightmembers until a desired level of uniformity is achieved; and, outputtinga specification for said display.
 14. The computer implemented methodaccording to claim 13 wherein said first set of components are lightemitting pixels and said at least one additional set of components areswitching electronics corresponding to said light emitting pixels. 15.The method according to claim 13 wherein desired level of uniformityoccurs when the difference between the reflectivities is less than aboutten percent.
 16. The method according to claim 13 wherein desired levelof uniformity occurs when the difference between the reflectivities isless than about five percent.
 17. The method according to claim 13wherein desired level of uniformity occurs when the difference betweenthe reflectivities is less than about three percent.
 18. The methodaccording to claim 13 wherein desired level of uniformity occurs whenthe difference between the reflectivities is less than about 0.5percent.